Phase Description: The Lux i-Amylose 3 chiral selector has complementary but distinct chiral selectivity in comparison to i-Amylose-1 and i-Cellulose-5.

However, even with all this luck, all your questions still might not be answered. See below for some of our most frequently asked chiral separation questions and answers.

Question: What is the difference between Amylose and Cellulose polysaccharide backbones?

Both backbones form 3-dimensional helical structures that are well suited to provide grooves and cavities for potential steric interactions, hydrogen bonding, dipole, and pi-pi based interactions. However, the structure for amylose is considered more tightly coiled in comparison to the looser cellulose structure, which in turn lends to different enantiomeric interaction profiles. Practically speaking, this difference backbone structure results in distinct selectivity for amylose and cellulose, even if the identical chiral selector is substituted, as the 3-dimensional orientation around the chiral stationary phase will differ.

Question: How do the aromatic functionalities of chiral compounds affect selectivity?

Generally, in chiral compounds, the proximity of aromatic groups to the stereocenter relates directly to the ease of achieving successful resolution of its enantiomers. For instance, the separations of enantiomers in which the aromatic functionality is 4 or more atoms away from the stereocenter is very challenging and chromatographically uncommon. Enantioselectivity is most effective when the distances between the aromatic group and stereocenter are equivalent in both conformations. If the aromatic group of the compound has electron withdrawing groups like halogens or oxygen containing functionality, it will be more electron deficient and will interact more effectively with electron-rich aromatic groups in the chiral column’s stationary phase (generally unsubstituted or with electron donating alkyl groups).

Question: Why does Phenomenex use DEA over TEA as the primary basic modifier in most application notes?

Both DEA (diethylamine) and TEA (triethylamine) are widely published as good basic modifiers for improving peak shapes while using polysaccharide-type columns. We chose DEA for our initial screening data and have continued with it to maintain consistency. TEA is just as effective and commonly used by a number of our customers on Lux polysaccharide chiral columns.

Have an enantiomeric pair of questions and want a judgement free answer? Reach out to our technical experts via Live Chat 24/7 at www.phenomenex.com/chat.

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